Articles such as preformed concrete building blocks, roof and floor tiles, paving slabs, structural members, and other articles have traditionally been formed from concrete comprising a mixture of cement, such as hydraulic or Portland cement, mineral aggregate, and water, plus various optional additives such as air entraining agents, water reducers, plasticizers, water proofing and possibly others. These materials may in some instances be combined with reinforcement such as steel bars, wires or fibres. The materials are generally blended in a concrete mixer and the resultant wet mixture is placed and densified in a mould or form to produce a desired shape. Hydration of the cement paste then takes place over a period of time after which the mould or form is removed to form the concrete article. Concrete formed in this manner has reasonable strength and durability in most environments, however the concrete typically takes many days or even weeks to harden to full strength.
Sulphur is readily available in many countries as a by-product of the oil and gas industry. The relatively low cost and unique properties of sulphur have led to its utilization as a construction material particularly to replace the use of Portland cement or asphalt cement. Sulphur concretes have been developed in which elemental or modified sulphur completely replaces the Portland cement.
However, it is important that consideration is given to the sustainability aspects of sulphur concrete, in particular, whether it can be readily recycled.
It has now surprisingly been found by the present inventors that crushed sulphur concrete can be used as aggregate in hydraulic cement-based concretes, particularly those based on Portland cement.